1. Field of the Invention
The present invention is generally related to a cowl for a marine propulsion system and, more particularly, to an air intake path through a cowl of an outboard motor.
2. Description of the Prior Art
Many different types of cowls are known to those skilled in the art of marine propulsion systems and outboard motors. A cowl for an outboard motor serves several purposes. It provides a covering for an engine of the outboard motor and also allows air to pass from the ambient surroundings of the outboard motor to the air intake of the engine. The cowl protects the engine from the normal splashing of water that is inherent in the use of an outboard motor on a marine vessel. Openings formed through the cowl allow air to pass from the ambient surroundings to the air intake ducts of the outboard motor engine.
Those skilled in the art of marine propulsion systems and, more particularly, outboard motors are aware that cowls should allow air to pass to the air intake system of the engine in an outboard motor while minimizing the passage of water toward the air intake system of the engine.
U.S. Pat. No. 6,132,273, which issued to Nakayama et al. on Oct. 17, 2000, describes a cowling for an outboard motor. The cowling arrangement provides atmospheric air to the engine of an outboard motor for engine cooling and combustion while inhibiting water intake. The protective cowling incorporates one or more air inlets, an air chamber, and ducts of different sizes for permitting atmospheric air to enter the engine compartment. One of these ducts, which is disposed in part above electrical components of the engine, is substantially shorter in length than the other duct. This duct thus has a smaller flow area without unduly restricting air flow through the duct. An air chamber cover is affixed to the engine and shields the ducts to afford further water preclusion.
U.S. Pat. No. 6,358,105, which issued to Isogawa et al. on Mar. 19, 2002, describes a cowling arrangement for an outboard motor. The arrangement is intended for use with an outboard motor that is powered by an internal combustion engine. The improved arrangement includes a flywheel cover and cowling that incorporate upwardly and downwardly extending ribs which are positioned along an air path between the air vent of the outboard motor and the throttle body of the motor. These ribs act as labyrinth-type seals which prevent water entering the air vent from contacting the throttle body. Also disclosed is an improved cowling arrangement that prevents water pooled on the flywheel cover from draining onto the throttle body when the motor is tilted, such as when the watercraft banks into a turn.
U.S. Pat. No. 5,938,491, which issued to Kawai et al. on Aug. 17, 1999, describes a cowling air inlet for an outboard motor. The cowl defines an air inlet opening for an outboard motor that facilitates the ingestion of large amounts of air at low velocity. This aids in the assurance that water is not ingested into the engine. The configuration of the inlet opening is such that the water that is separated by the inlet system can easily flow away from the inlet opening and also the water that collects on the housing surfaces can be easily separated and will drain away from the actual inlet openings into the interior of the cowling.
U.S. Pat. No. 6,296,536, which issued to Katayama et al. on Oct. 2, 2001, describes a cowling assembly for an outboard motor. A cowl includes an improved construction that can supply relatively cool air containing little or no water to the induction device and that can also supply air to cool engine components without reducing the charging efficiency. The outboard motor has an engine that includes an air induction device and is enclosed by the cowling. The induction device has an air inlet opening.
U.S. Pat. No. 5,391,099, which issued to Allain on Feb. 21, 1995, describes an air intake protector for an outboard motor. A cowling for enclosing a marine propulsion unit with a recess having a port that communicates air to the engine is described. A plate having spaced-apart openings is received on the port. A diverter screen covers the openings. The diverter screen is adapted for communicating air from the openings through a diverter screen to the port and for restricting flow of water therethrough.
U.S. Pat. No. 5,328,395, which issued to Oishi on Jul. 12, 1994, describes a cowling structure for a marine propulsion engine. An outboard motor and particularly an improved protective cowling for an outboard motor is described which provides a very simple air inlet but one which is effective in preventing the passage of water to the interior of the protective cowling and for separating and draining water from the inducted air. The drained water is returned directly to the atmosphere. The air inlet system for the protective cowling is formed by only two members so as to facilitate a simple and low cost construction.
U.S. Pat. No. 5,937,818, which issued to Kawai et al. on Aug. 17, 1999, describes a ventilation system for an outboard motor. A ventilating system for an outboard motor having a water propulsion device and an internal combustion engine positioned in a cowling is described. The engine has an output shaft arranged to drive the water propulsion device. The ventilating system includes an air inlet in the cowling which permits air to flow into an engine compartment in which the engine is disposed and an exhaust port positioned in the cowling. The system also includes a mechanism for drawing air through the cowling into the compartment and expelling air out of the compartment through the exhaust port after the engine has stopped.
U.S. Pat. No. 5,046,976, which issued to Kobayashi et al. on Sep. 10, 1991, describes a cowling and air intake duct for an outboard motor. The air intake device is provided for the powerhead of an outboard motor which includes an air intake duct with a downwardly facing opening. The duct is mounted within an air inlet cavity formed within an upper rear portion of the cowling. A cover is secured to the cowling to form the top surface of the air inlet and to cover the intake duct. The air inlet inducts air from the atmosphere to a rearwardly facing opening wherein the air is drawn up into the intake duct for supply to the induction system of the outboard motor's internal combustion engine. The downwardly facing intake duct insures that water will not enter into the interior of the cowling or into the engine induction system.
U.S. Pat. No. 5,277,633, which issued to Kato et al. on Jan. 11, 1994, describes a cowling for a marine propulsion engine. The cowling structure for a marine propulsion engine effectively prevents water from entering into the air intake opening while at the same time maintaining optimum engine performance. The cowling structure has an engine cowl which encloses the engine and which defines an air intake opening. An air duct molding is associated with the engine cowl such that it extends over the air intake opening and, in conjunction with the engine cowl, defines an air inlet facing toward a rear portion of the cowling structure. A wall extends between the engine cowl and the air duct molding and is located between the air intake opening and the air inlet. Sidewalls, which are spaced apart a distance less than the width of the wall, direct any water entering the air inlet towards the wall to effectively prevent the water from entering the air intake opening.
U.S. Pat. No. 5,181,870, which issued to Arai et al. on Jan. 26, 1993, describes a cowling and air inlet device for an outboard motor. Several embodiments of a cowling and air intake device for a powerhead of an outboard motor are disclosed. These include an air inlet formed in an upper rear surface of the cowling and an air intake duct formed within the air inlet for supplying air to the engine induction system. Various arrangements of partitions are provided within the air inlet for permitting adequate air flow to the engine induction system but preventing water from entering the interior of the cowling and the engine induction system.
U.S. Pat. No. 6,669,517, which issued to Alby et al. on Dec. 30, 2003, discloses a multiple part cowl structure for an outboard motor. A cowl structure comprises first and second cowl members that are independent components. A first cowl member is attachable, by a latch mechanism, to a support structure of the outboard motor. The second cowl member is attachable by a latch mechanism, to both the first cowl member and the support structure. The first cowl member extends across a rear portion of the outboard motor and at least partially along both port and starboard sides of the outboard motor. The second cowl member extends across a front portion of the outboard motor and at least partially along the port and starboard sides of the outboard motor. In a preferred embodiment, the second cowl member also extends partially over a top portion of the outboard motor and over a rear portion of the outboard motor.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
As can be seen in a review of the above referenced United States patents, many different techniques are known, and have been used, to allow air to freely flow through the cowl structure toward the air induction system of an engine while inhibiting the flow of water in that same direction. Many different structures have been incorporated in cowl devices which inhibit or prevent water from flowing into the engine's air induction system while allowing air to flow from the ambient surroundings of the outboard motor, external to the cowl, to the air induction system of the engine.
It would be significantly beneficial if an air flow system could be provided which directs a flow of air through the structure of a cowl while preventing the flow of water into the air induction system of the engine in such a way that the devices used to inhibit the water flow do not adversely reduce the efficiency of the air flow.